I'd also like to know this.
I know that if you restore an iTunes backup of one device onto another device (e.g. you've bought a new iPhone, or you had one replaced), certain items such as the email & WiFi passwords are not restored as they are encrypted with the unique hardware ID of the device that made the backup (unless, as mentioned, you chose to "encrypt" the backup with a password in iTunes).
But what about iCloud?
e.g. If I restored an iCloud backup of my current iPhone onto a nice new iPhone 5, would it restore my email & WiFi passwords etc., or would they need to be re-entered? I would prefer it that they would need to be re-entered, as I don't like the idea of critical keychain data being accessible on another device, as if someone ever compromised my Apple ID they could then restore *everything* including email passwords etc. onto their own device by stealing my iCloud backup.
Does anyone have a definitive answer for this?
I have read some reports of people setting up a new iPhone 5 using an iCloud backup of a previous iPhone, and having *everything* right there including items such as email passwords that surely should have been tied solely to the original device. Is this true?
Nope.....found out the hard way.
For some strange reason when I restored a iPad my saved Keychains were deleted.
I called Apple and spoke with a high level Engineer and after trying to retrieve my Keychains from a Time Machine backup (nearly 2 hrs of trying) we were never able to retrieve them. On a positive note he said that's a major issue that has to be addressed, and would get back to me with a fix.
Looks like 1Password is the only sure fire way to insure your passwords are backed up.....at least for now.